The present invention relates to plastic pallet and more particularly to a pallet made of synthetic resin for use with a fork lift.
Heretofore, the material most commonly used for constructing a pallet for a fork lift has been lumber. However, lumber is not entirely satisfactory because of certain natural deficiencies, such as, for example, that the resources thereof as material are limited, its supply situation is unstable and a product made therefrom generally has poor chemical resistance and requires complicated manufacturing methods. Metallic pallets also are available, but they are expensive, and therefore, more recently, attempts have been made to produce a plastic pallet.
As is well known, however, the pallet for a fork lift is usually constructed from two sheets of deck board joined by parallel girder materials provided at their respective opposite edges and intermediate portions, whereby a space is provided between the girder portions for receiving the fork. Therefore, a shortcoming of a plastic pallet is that it compares unfavorably with the wooden or metallic pallet in the consideration of strength and resistance to bending because of the natural characteristics of plastic.
Also, since the pallet for a fork lift is, as described hereinabove, a hollow body having a fork-inserting mouth, a one-step molding process, such as, for example, an injection molding process using a thermoplastic material, would require a metallic mold equipped with a sliding core. One step injection molding of a pallet is very difficult, therefore, with conventional molding machines because they are so large.
Furthermore, it is difficult to obtain a plastic pallet which is characteristically comparable to the wooden or metallic pallets in bending strength, even by such means as compression molding, extrusion molding and the like, because the pallet for a fork lift has the particular construction described hereinbefore.
In addition, an enormous molding machine would be required for molding an item such as a pallet having large dimensions and weight, and, therefore, such a pallet becomes remarkably expensive, both for its high initial cost and for its general maintenance.